Title

Author

Date of Award

2001

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

First Advisor

Robin L. McCarley

Abstract

Ultra-thin films of Au are formed on glass by thermal evaporation of Au onto a silane-modified glass surface. Monolayers of 3-aminopropyltriethoxysilane on glass (APS/glass) are outstanding surfaces for the formation of adherent, electrically conductive, smooth, and highly oriented Au films. Scanning tunneling microscopy images indicate that ultra-thin Au films are highly conductive and have a significant {111} texture, and X-ray diffraction studies confirm the latter. In addition, Au films on APS/glass surface are not removed by tape tests, pointing to a strong chemical interaction between the Au and amine surface. Unlike metal adhesion promoters, APS layer does not diffuse through Au films, making their use in advanced devices attractive. Two applications of the Au films on APS/glass substrates are described. First, Au band electrodes with widths ranging from 3 to 150 nm are investigated by obtaining the voltammetric response of a series of substituted ferrocenes in non-aqueous electrolyte. Plots of normalized limiting current for each ferrocene derivative as a function of normalized electrode width reveal a negative response from traditional theoretical predictions. The observed negative responses for electrodes less than 50 nm in width are explained by effects that become important when the sizes of electrode and redox species are comparable. Concerns regarding the real surface area of band electrodes are addressed by labeling of the exposed Au of nanoband electrode with ferrocene-alkanethiol and measurements of double-layer capacitance. Microscopy studies of the epoxy/Au/glass interface point to insufficient insulation of the Au by the epoxy as the result of defects. Lastly, fabrication methods in previous studies are used to construct laterally patterned metal features through the use of photolithography techniques. A photoprotecting group, nitroveratryloxycarbonyl, is covalently linked to the amine group of the APS monolayers. The sample is patterned by using a mask that allows UV light to reach the nitroveratryloxycarbonyl-APS/glass surface and remove the nitroveratryloxycarbonyl groups in the exposed areas. Gold is then vapor deposited on the patterned surface and the success of the patterning experiments are evaluated by "developing" the Au through the removal of tape.